MN3005 Echo no treble

[benfox]

Hi
I built a echo chamber it works very well but the sound has not a lot of treble. I think they are cut off by something in the device but i don't know if it is the MN3005 IC or a cap. Every thing is ok in my box i've check it several times but i took the schematic from the datasheet of the 3005 so maybe there is a mistake. If someone has ever did this stuff help me please.
Maybe it's becaus e my MN3005 is an old part here is the link to the datasheet : http://www.alldatasheet.com/datasheet-pdf/view/PANASONIC/MN3005.html
It sound like old echo chambers it's nice but the sound it's a bit "mute"
Thanx
benfox

[Mark Hammer]

That lack of treble may very be built into the circuit.

BBD circuits can produce a lot of noise because of the fact that they are "clocked".  The longer the delay aimed for, the slower the clocking, and the greater the risk of the clock frequency being in the range of human hearing.  

There are better and worse solutions to this built-in problem.  One of the worst is to use simple lowpass filters that are set low enough that little clock noise finds its way to the circuit output.  That may be what you used.

The thing to understand about filters is that their rolloffs are gradual.  If a filter has a calculated corner frequency of 5khz, for example, there is still 8khz, 12khz, and 15khz content coming through, just not as much of it.  So, the produce enough reduction of potential high frequency content at the output, a simple filter needs to start its rolloff much lower down.

If the filters are more complex, however, say 5-pole instead of 3-pole, one can get away with moving the rolloff frequency upwards a little and letting a little more treble through.  The steepness and greater selectivity of the more complex filter will mean that content just above the rolloff will be sufficiently attenuated to "buy you the freedom" to tolerate more upper midrange and lower treble without having to pay too big a noise price.

The next step up is to use a combination of companding AND more complex filtering.  Whatever the lowpass filters don't take out, the companding will.  This generally lets the user/designer aim for much more bandwidth.

Put quite simply, it is possible the circuit you are using sacrifices treble so as to get the most delay with the fewest parts.

[benfox]

That what i've finally found on the web thanx for the details ! I expected nnot that much ! I ha ve find a way to play with this stuff with more treble. I've plugged in parralel a second and direct way to my amp (surprise no feedback until a certain vomlume)) nand it work very well like that cause the original sound is mixed with the delayed sound. I use a stereo spliter to sp)lit the signal of my guitar. That's a good way to mix two different sound you can use this  with 2 different distortin also and it's usefull if you want rich sound. Just an easy way to have a better sound....i'm shure i'm not the only one.....
Thank you Mark and keep being so clear that's nice  :lol:
Have a nice day every body i'm happy today i don't know why
 :lol:  :wink:

[Mark Hammer]

i'm happy today i don't know why
 :lol:  :wink:

C'est vendredi, mon ami, c'est vendredi, et même c'est le 13me, c'est encore vendredi. :wink:

[scratch]

Mark, votre francais est tres bien!
Much better than mine ... although my mother tongue is French, all my technical training (college) was in English, I've not had to write french since high school. When I do now, I get one of my peers to review it before sending it out to customers.

Et oui bonne chose que c'est vendredi!

[benfox]

scratch
On peu peut etre essayer de communiquer sur nos trucs en francais ca changerais non
J'ai plein de schémas pour toi !!!
benfox
from grenoble france

[Mark Hammer]

Malgré que l'anglais sert le plus grand pourcentage de personnes ici, il y avait une très grande augmentation de membres qui postent de la France pendant les 12 mois précédants.  J'acceuille tout qui parle les langues autrement que l'anglais, et j'applaude leurs efforts d'apprendre (et de maitriser!) une langue autrement que leur premier.  Que nous reste soyons aussi travailleurs!

(Traduction: I think it's nice to see so many people from so many other languages here.  As a native anglophone, I am always impressed by the efforts that people with other first languages put into learning English.  We could all learn a thing or two from that diligence.)

J'ai honte de dire que je suis un produit des éxigeances de mon poste.  Actuèllement, je fait le dernier tour de piste (le 5me du 5 mois) de ma formation linguistique gouvernmentale.  J'aurai mon éxamen (orale; j'ai déja réussi mes éxamens écrits) le 9 juin.

Ben,

Donne un coup d'oeil au projet "AD3208" de Scott Swartz à GGG.  Ce projet utilise un pair de BL3208 (disponible) au lieu d'un seule MN3205 (comparativement indisponible), et le PCB est capable d'utiliser les deux (même un MN3205 pi un AD3208 en même temp).  Le circuit emploit un compander NE570/571 ET le filtrage afin de reduire le bruit.  Avec les deux en place, c'est possible d'utiliser le filtrage moin sèvère.

Note qu'il y a certaines changements ou differences entre un MN3205 et un MN3005, mais ces differences sont pas assez grandes d'empecher l'utilisation du même PCB.  Un autre avantage c'est que le PCB est deja pret pour un autre chip si t'est assez chanceux d'en trouver un autre dans l'avenir.[/i]

[benfox]

enfin du francais merci mon dieu !!!
Ton francais est assez bon malgres quelques fautes qui font sourire...
Je pense que je vais garder ma chambre d'echo comme elle est Je me suis habituer à son grain de son un peu sourd qui me rappelle les sons de 60's.
Si tu veux travailler ton francais ne regarde pas mon orthographe qui est déplorable !!! :!:
Bonne chance pour tes examen même si je n'ais pas bien compris de quoi il s'agissais
benfox

[cd]

If you look at the MN3005 datasheet circuit, it's no wonder there's no treble.  Let's look at it stage/stage:

Input stage is an INVERTING opamp stage with a relatively low input Z (120k) which means it's going to load down the guitar - treble loss right there.  Also, the input to that stage has a LPF at 400Hz turnover (!) which kills highs completely there as well.

After the input stage, there are two other LPFs with a turnover at 860Hz!!  Bye bye more highs!   That in turn goes into another inverting stage (driven by a low Z stage so no high loss here) which then goes into the BBD.

After the BBD comes more LPFs to get rid of the clocking noise (these have a 2kHz corner frequency) until you get to the output driving stage and echo control.

If you're too lazy to look up the datasheet, here's the schem:



In short, the datasheet circuit is lousy (at best) for guitar - it might not be too bad for vocals or if your CD player was the input.  If you were going to tweak things for guitar, add a high Z input buffer stage, change the input LPF corner frequencies to something more reasonable (like 2kHz), and the LPFs on the BBD output to maybe 7kHz (or whatever your MN3101 is clocked at).

[Mark Hammer]

Funny, isn't it, how sometimes the application circuit shown in datasheet/appnote files is great and needs few changes to do what we folks here need (the Q&D Compressor, based on the SSM2166 is a great example of that, and assorted LM386 circuits are another).  Other times the sample circuit is barely enough to find out if the device "works".  In this instance, the builder who doesn't work their way through the math involved, or who may understand the math well enough but not the real-world application, may come to a frustrating conclusion about the chip if they build the circuit shown in the appnote.

Je suppose que le meilleur conseil serait de demander au forum avant de tenter quelque chose décrit dans un datasheet.

En anglais:  Look before you leap!

Ben,

Merci de ton encouragement.  Je travaille comme fonctionnaire fédérale, et l'examen s'adresse simplement la facilité orale dans l'autre langue officielle.  Les francos ont leur propre examen en anglais aussi.  D'habitude, les sujets de conversation s'agissent d'activités reliées au travaille, comme les taches, structure de l'organisation, les politiques ou mandats des ministères, etc.  Un peu de subjonctif ici, un peu de conditionelle passé la, quelques adjectifs bien choisi, libérallement et légerement parsemés partout, et je serai libre.  Je suis certain que, parmi mes mauvaises conjugations (ma Béscherelle est ailleurs), mes erreurs de genre, le manque d'accord, etc., que ce texte est plein d'erreurs.  Grace é Dieu, l'éxamen est orale et certaines erreurs devienent invisible dans ces circonstances.   J'assiste l'école à plein temp quotidiennement....pour le moment.  J'ai hâte de retourner au travail en juin.